Scattered-photon extraction-based fixtures

ABSTRACT

A light fixture includes a light source, a wavelength-conversion material, and a reflector. The light source is configured to emit a first radiation, and has a front surface and a back surface. The wavelength-conversion material is arranged under the front surface and configured to convert the first radiation to a second radiation which has a first portion not able to reach the reflector and a second portion able to reach the reflector. The reflector is arranged over the back surface and configured to reflect the second portion away from the light source without passing through the wavelength-conversion material. The reflector has an end distant from the light source and is arranged in an elevation different from that of the wavelength-conversion material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/152,172, filed Jan. 10, 2014 which is a continuation of U.S. patentapplication Ser. No. 13/581,861, filed Nov. 6, 2012 (now U.S. Pat. No.8,646,927), which is the U.S. National Phase application ofPCT/US2011/028069, filed Mar. 11, 2011 which is a continuation of U.S.application Ser. No. 12/947,899, filed Nov. 17, 2010 (now U.S. Pat. No.8,764,225), which is a continuation of U.S. application Ser. No.11/642,089, filed Dec. 20, 2006 (now U.S. Pat. No. 7,837,348) which is acontinuation-in-part application of U.S. application Ser. No.10/583,105, filed Apr. 23, 2007 (now U.S. Pat. No. 7,819,549), entitled“High Efficiency Light Source Using Solid-State Emitter AndDown-Conversion Material,” which is the 371 National Phase ofInternational Application No. PCT/US2005/015736, filed May 5, 2005,which claims the benefit of priority to U.S. Provisional ApplicationSer. No. 60/568,373, filed May 5, 2004 and to U.S. ProvisionalApplication Ser. No. 60/636,123, filed Dec. 15, 2004. This applicationalso claims priority to U.S. Provisional Application Ser. No.61/339,958, filed Mar. 11, 2010. The disclosures of all of theseapplications are incorporated in their entirety by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to solid-state lighting.Specifically, the present invention relates to highly efficient lightingfixtures using solid-state light (SSL) sources, optic elements, heatsinks, and a remote wavelength-converting material.

BACKGROUND OF THE INVENTION

Solid-state light (SSL) emitting devices, including solid-state lightfixtures having light emitting diodes (LEDs) are extremely useful,because they potentially offer lower fabrication costs and long termdurability benefits over conventional light fixtures, such as those thatutilize incandescent and fluorescent lamps. Due to their long operation(burn) time and low power consumption, solid-state light emittingdevices frequently provide a functional cost benefit, even when theirinitial cost is greater than that of conventional lamps. Because largescale semiconductor manufacturing techniques may be used, manysolid-state light fixtures may be produced at extremely low cost.

In addition to applications such as indicator lights on home andconsumer appliances, audio visual equipment, telecommunication devicesand automotive instrument markings, LEDs have found considerableapplication in indoor and outdoor informational displays. For example,LEDs may be incorporated into overhead or wall-mounted lightingfixtures, and may be designed for aesthetic appeal.

With the development of efficient LEDs that emit blue or ultraviolet(UV) light, it has become feasible to produce LEDs that generate whitelight through wavelength conversion of a portion of the primary emissionof the LED to longer wavelengths. Conversion of primary emissions of theLED to longer wavelengths is commonly referred to as down-conversion ofthe primary emission. This system for producing white light by combiningan unconverted portion of the primary emission with the light of longerwavelength is well known in the art. Other options to create white lightwith LEDs include mixing two or more colored LEDs in differentproportions. For example, it is well known in the art that mixing red,green and blue (RGB) LEDs produces white light. Similarly, mixing RBGand amber (RGBA) LEDs, or RGB and white (RGBW) LEDs, are known toproduce white light.

Recent studies have determined that the heat generated from LEDsdecreases overall light emission and bulb durability. More particularly,the LED device becomes less efficient when heated to a temperaturegreater than 100° C., resulting in a declining return in the visiblespectrum. Extended operation, and the resulting exposure to high heat,also reduces the effective life of the LEDs. Additionally, the intrinsicwavelength-conversion efficiency for some down conversion phosphors alsodrops dramatically as the temperature increases above approximately 90°C. threshold.

The amount of light emission directed into the particular environmentmay be increased by the use of reflective surfaces, which is also wellknown in the art. Reflective surfaces have been used to direct lightfrom the LED to the wavelength-conversion material and/or to reflectdown converted light which is generated from the wavelength-conversionmaterial. Even with these improvements, the current state of the art LEDtechnology is inefficient in the visible spectrum. The light output fora single LED is below that of traditional light fixtures such as thosewhich utilize incandescent lamps, which are approximately 10 percentefficient in the visible spectrum. To achieve comparable light outputpower density to current light fixture technology utilizing incandescentlamps, an LED device often requires a larger LED or a design havingmultiple LEDs. However, designs incorporating a larger LED or multipleLEDs have been found to present their own challenges, such as heatgeneration and energy utilization.

SUMMARY OF INVENTION

To meet this and other needs, and in view of its purpose, the presentinvention provides a scattered photon extraction light fixture includingan optic element having a first surface and at least one substantiallytransparent sidewall extending from the first surface; a light sourcefor emitting short wavelength radiation, the light source disposed at anend of the at least one substantially transparent sidewall opposite thefirst surface of the optic element; a wavelength-conversion material,disposed on the first surface of the optic element, for receiving anddown converting at least some of the short wavelength radiation emittedby the light source and back transferring a portion of the received anddown converted radiation; and one or more reflectors positioned oppositethe wavelength-conversion material, such that the light source ispositioned between the wavelength-conversion material and thereflectors, for reflecting at least some of the radiation extracted fromthe optic element through the at least one substantially transparentsidewall; wherein the at least one substantially transparent sidewall isconnected at one end to the first surface containing thewavelength-conversion material and at another end to the light source,and wherein the substantially transparent sidewall is configured to passradiation back-transferred from the wavelength-conversion materialoutside of the light emitting apparatus.

The light fixture may further include a wavelength-converting materialdisposed on at least one or more other walls, such as one or moretransparent sidewalls, of the optic element. Similarly, the lightfixture may further include a heat sink affixed or adjacent to the lightsource. In some embodiments, the heat sink may be affixed on one side toat least one substantially transparent sidewall and on another side toone or more reflectors. The light fixtures of the present invention maybe, for example, extruded or revolved light emitting fixtures. The lightfixtures may also include one or more suspension mechanisms forinstallation, for example, to a wall, as in a wall-mounted lightfixture, or to a ceiling, as in a suspended light fixture. The lightsource may be at least one semiconductor light emitting diode, such as alight emitting diode (LED), a laser diode (LD), or a resonant cavitylight emitting diode (RCLED). Additionally or alternatively, the lightsource may be an array of more than one light emitters, such as an arrayof LEDs. A number of different types of LEDs may be employed as thelight source. For example, when an array is used as the light source,the array may include one or more LEDs of the same or of differenttypes. The light sources may be selected to improve energy efficiency,control the color qualities of the emitted light, or for a number ofother reasons, such as aesthetics. The wavelength-converting materialmay be include one or more materials, such as phosphors, quantum dots,quantum dot crystals, and quantum dot nano crystals, and mixturesthereof.

In another embodiment, the present invention provides an extrudedscattered photon extraction light fixture including a light source foremitting short wavelength radiation, the light source comprising one ormore light emitters; an elongated tube optic element having at least onesubstantially transparent surface; a wavelength-conversion material,disposed on or integrated with at least one surface of the optic elementand remote from the light source, for receiving and down converting atleast some of the short wavelength radiation emitted by the light sourceand back transferring a portion of the received and down convertedradiation; and one or more reflectors positioned opposite thewavelength-conversion material, such that the light source is positionedbetween the wavelength-conversion material and the reflectors, forreflecting at least some of back transferred portion of the received anddown converted radiation; wherein the light fixture is configured suchthat some radiation may be reflected back towards the light source asunconverted light radiation, some light may be transferred through thewavelength-conversion material without being converted, and someradiation is converted and may be forward transferred or backtransferred by the wavelength-conversion material; and wherein the lightfixture is configured to capture substantially all of the forwardtransferred and the back transferred converted light by the arrangementof the light source, optic elements, and reflectors.

In yet another embodiment, the present invention provides a scatteredphoton extraction light fixture including a light source for emittingshort wavelength radiation, the light source comprising one or morelight emitters, affixed to a first optic element; awavelength-conversion material, disposed on or integrated with a secondoptic element, for receiving and down converting at least some of theshort wavelength radiation emitted by the light source and backtransferring a portion of the received and down converted radiation; anda reflective surface affixed at one side to the first optic element toform a reflective enclosure containing therein the second optic elementand the wavelength-conversion material, for reflecting at least some ofback transferred portion of the received and down converted radiation;wherein the second optic element and wavelength-conversion material aresuspended within the reflective surface and remote from the lightsource.

In still another embodiment, the present invention provides a scatteredphoton extraction light system including a plurality of light emittingfixtures. Each of the plurality of light emitting fixtures includes anoptic element having a first surface and at least one substantiallytransparent sidewall extending from the first surface; a light sourcefor emitting short wavelength radiation, the light source disposed at anend of the at least one substantially transparent sidewall opposite thefirst surface of the optic element; a wavelength-conversion material,disposed on the first surface of the optic element, for receiving anddown converting at least some of the short wavelength radiation emittedby the light source and back transferring a portion of the received anddown converted radiation; and one or more reflectors positioned oppositethe wavelength-conversion material, such that the light source ispositioned between the wavelength-conversion material and thereflectors, for reflecting at least some of the radiation extracted fromthe optic element through the at least one substantially transparentsidewall; wherein the at least one substantially transparent sidewall isconnected at one end to the first surface containing thewavelength-conversion material and at another end to the light source,and wherein the substantially transparent sidewall is configured to passradiation back-transferred from the wavelength-conversion materialoutside of the light emitting fixture.

In a further embodiment, the present invention provides a scatteredphoton extraction light fixture including an optic element having afirst surface with two opposite edges and one or more secondarysurfaces, wherein the one or more secondary surfaces are tangentially orperpendicularly connected at each edge of the first surface; one or morelight emitters for emitting short wavelength radiation, the one or morelight emitters disposed on the one or more secondary surfaces of theoptic element; a wavelength-conversion material, disposed on the firstsurface of the optic element, for receiving and down converting at leastsome of the short wavelength radiation emitted by the emitters andforward transferring a portion of the received and down convertedradiation; and one or more reflectors positioned opposite the one ormore light emitters, such that the wavelength-conversion material ispositioned between the one or more light emitters and the reflectors,for reflecting at least some of the forward transferred radiationthrough the optic element; wherein the one or more secondary surfacesare each connected at one end to the first surface containing thewavelength-conversion material and at another end to the one or morereflectors, and wherein the one or more secondary surfaces areconfigured to pass radiation back-transferred from thewavelength-conversion material outside of the light emitting fixture.

The wavelength-conversion material, in the embodiments of the presentinvention, is disposed remotely, i.e., away from the light source(s).One or more wavelength-converting materials are used to absorb radiationin one spectral region and emit radiation in another spectral region,and the wavelength-converting material can be either a down-convertingor an up-converting material. Multiple wavelength-converting materialsare capable of converting the wavelength emitted from the light sourceto the same or different spectral regions. The wavelength-conversionmaterials may be mixed together or employed as individual layers. Bycapturing both the forward transferred portion and the back transferredportion of the down-converted light, system efficiency may be improved.Similarly, the position of the down-conversion material and thereflector, when one or more reflectors are utilized, may be adjusted toensure that light from the light source impinges the down-conversionmaterial uniformly to produce a uniform white light and allowing more ofthe light to exit the device. Heat sinks may be utilized to reduceand/or redistribute heat at the light source(s). At the same time,positioning the down-conversion material remote from the light sourceprevents light feedback back into the light source. As a result, theheat at the light source is further minimized and results in improvedlight output and life. All of these structural parameters and featuresenable increased light production, enhanced lighting efficiency, andimproved energy utilization in comparison to known technologies.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasizedthat, according to common practice, the various features of the drawingare not to scale. On the contrary, the dimensions of the variousfeatures are arbitrarily expanded or reduced for clarity. Included inthe drawing are the following Figures:

FIG. 1 is an illustration of a method of producing visible light using asolid-state light emitting diode (LED) and a wavelength-convertingmaterial according to an exemplary embodiment of the present invention;

FIG. 2(a) is an illustration of a solid-state light source lightfixture, in accordance with one embodiment of the present invention;

FIG. 2(b) illustrates a cross-sectional view of the solid-state lightsource light fixture shown in FIG. 2;

FIG. 2(c) illustrates an expanded view of FIG. 2(b) showing the heatsink and the solid-state light emitting diode (LED);

FIG. 3 is an illustration of a solid-state light source light fixture,in accordance with another embodiment of the present invention;

FIGS. 4(a)-4(f) illustrate cross-sectional views of other embodiments ofthe present invention which include one or more light sources,wave-length conversion materials, heat sinks, and optic elements;

FIGS. 5(a)-5(d) illustrate cross-sectional views of other embodiments ofone or more light sources, wave-length conversion materials, heat sinks,and optic elements, in accordance with other embodiments of the presentinvention;

FIGS. 6(a)-6(c) illustrate a cross-sectional view of one or more lightsources, wave-length conversion materials, heat sinks, and opticelements, when combined with a reflector, in accordance with otherembodiments of the present invention;

FIG. 7(a) illustrates a wall-mounted lighting fixture according to anembodiment of the present invention;

FIG. 7(b) illustrates the lighting fixture of FIG. 7(a) configured as asuspension from a ceiling, in accordance with another embodiment of thepresent invention;

FIG. 7(c) illustrates a cross-sectional view of the lighting fixturesshown in FIGS. 7(a) and 7(b);

FIG. 7(d) illustrates an expanded view of FIG. 7(c) showing the heatsink, optic elements, and the solid-state light emitting diode (LED);

FIG. 8(a) illustrates a lighting fixture according to another embodimentof the present invention;

FIG. 8(b) illustrates a cross-sectional view of the lighting fixtureshown in FIG. 8(a), according to an embodiment of the present invention;

FIG. 8(c) illustrates a variation on the lighting fixture shown in FIGS.8(a) and 8(b) which employs a compound reflector, according to anotherembodiment of the present invention;

FIGS. 9(a)-9(b) illustrate lighting systems, according to anotherembodiment of the present invention, which employ multiple lightingfixtures;

FIG. 10(a) illustrates a lighting fixture similar to that shown in FIG.2(a) but without reflectors;

FIG. 10(b) illustrates the results of a ray tracing computer simulationshowing the light output of the lighting fixture shown in FIG. 10(a).

DETAILED DESCRIPTION OF THE INVENTION

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

In U.S. Pat. No. 7,750,359, the inventors of the present invention havepreviously discovered the use of wavelength-converting materials toproduce a broad bandwidth light having the desired chromaticity valueand luminous efficacy while increasing the color rendering index (CRI)and lowering the correlated color temperature (CCT) of the output light,and increasing the efficiency of the device. In InternationalPublication No. WO 2010/144572, the inventors of the present inventiondiscovered and disclosed the benefits obtained by moving thewavelength-converting material to be remote, i.e., away, from the lightsource. By moving the wavelength-converting material away from the lightsource, more of the converted light can be extracted and the efficacy ofthe light device can be improved. Additional benefits were discoveredutilizing a heat sink adjacent to, and/or integrated with, the lightsource. This method of producing light was described as a scatteredphoton extraction (SPE) technique. The SPE technique was found toincrease light production, improve heat dissipation, and result inprolong light device durability and life span. These references, whichutilized the SPE technique in an SSL-based lamp bulb as a replacementbulb for incandescent lamps, are incorporated herein by reference intheir entirety.

The inventors have now discovered that the SPE technique can be utilizedto produce highly efficient lighting fixtures and lighting systems.Existing fixtures which utilize light emitting diode (LED) chips forgeneral lighting applications have been found to have lower luminousoutput when compared with traditional light sources. To overcome thisdeficiency, existing LED-based fixtures have utilized arrays of LEDs toachieve the required light level on the target surfaces. Existingmethods thus result in increased costs, higher energy consumption, andadditional thermal management issues, among other disadvantages. Thelighting fixtures of the present invention, which utilize the SPEtechnique and, optionally, structured optical elements, are able toproduce increased light emission using fewer LEDs and less electricalenergy. The lighting fixtures of the present invention also potentiallyreduce manufacturing and operation costs.

The present invention addresses these problems by utilizing the SPEtechnique, which positions the light source at a point away from thewavelength-converting material. One or more optic elements can bepositioned between the light source and the wavelength-convertingmaterial. Additionally, heat sinks and reflectors may be utilized invarious configurations. The light source may be at least onesemiconductor light emitting diode, such as a light emitting diode(LED), a laser diode (LD), or a resonant cavity LED (RCLED). Embodimentsof the present invention may utilize a single SSL source, such as asingle LED, or may include multiple SSL sources (i.e., a plurality ofLEDs in an array) as the light source. As known in the art, a number ofdifferent types of LEDs may be employed as the light source. Forexample, when an array is used as the light source, the array mayinclude one or more LEDs of the same or of different types. The lightsources may be selected to improve energy efficiency, control the colorqualities of the emitted light, or for a number of other reasons, suchas aesthetics. The light source may be coupled to a heat sink, with atleast a portion of the heat sink open to the environment to promote thedissipation of heat. The heat sink functions as a heat dissipationelement for the light source, enabling heat to be drawn away from thelight source. The heat sink may also provide mechanical support to thelight source. For example, the heat sink may be substantially affixed tothe optic element and coupled to the light source residing within theoptic element. This coupling effectively retains the light source withinthe optic element. The heat sink may additionally be substantiallyaffixed to one or more reflectors. These structural features of thepresent invention enable the SSL-based lighting fixture to have veryhigh luminous efficacy values and produce light levels similar to, orgreater than, traditional lighting fixtures such as fluorescent orincandescent lighting fixtures. The configuration of the presentinvention, and the utilization of the SPE technique, also prolonging thelife span durability of the SSL-based light source.

The use of wavelength-converting materials aids in the production oflight that is aesthetically similar to that which is produced bytraditional light fixtures, such as those which utilize incandescentA-lamps. As described above, the wavelength-converting material of thepresent invention may be composed of one or more materials adapted toabsorb radiation in one spectral region and emit radiation in anotherspectral region, and the materials can be either a down-converting or anup-converting material. As such, embodiments of the present inventionmay incorporate wavelength-converting materials that aredown-converting, up-converting, or both. It will be appreciated that theterms “down conversion,” “down converting,” and “down-converted” referto materials which are adapted to absorb radiation in one spectralregion and emit radiation in another spectral region. Accordingly, theterm “down conversion material” is defined as materials that can,through their composition, absorb radiation in one spectral region andemit it in another spectral region.

As light emitted from the light source reaches the wavelength-convertingmaterial, the wavelength-converting material absorbs the wavelengthlight and emits converted light. For example, when thewavelength-converting material includes down-converting material, thedown-converting material absorbs short wavelength light and emits downconverted light. The emitted down converted light may travel in alldirections (known as a Lambertian emitter), and therefore, a portion ofthe down converted light travels upwards while another portion travelsdownwards. The light that goes upwards (or outwards) from the downconversion material is the forward transmitted portion of the light andthe light that comes downwards towards the light source is the backtransmitted portion. This is explained further below with reference toFIG. 1.

The fixtures of the present invention implement the remotewavelength-conversion concept associated with the SPE technique. In asystem employing a remote down-conversion material, short wavelengthradiant energy from the light source is emitted towards adown-conversion material which is positioned away from the light source.At least a portion of the radiant energy hitting the down-conversionmaterial is down converted to a longer wavelength radiation and, whenboth radiations mix, results in a white light similar to the lightproduced by a traditional light fixture. The wavelength-conversionmaterial may be composed of one or more down-converting materialsadapted to absorb radiation in one spectral region and emit radiation inanother spectral region. The wavelength-conversion materials may bemixed together or employed as individual layers. Multiplewavelength-converting materials are capable of converting the wavelengthemitted from the light source to the same or different spectral regions.Accordingly, the wavelength-converting materials may comprise one ormore down-converting materials, up-converting materials, or both, whichmay be selected to produce the desired light output and color rendingproperties.

FIG. 1 shows a method of producing visible light using a solid-statelight emitting diode (LED) 102 and a wavelength-converting material 104,according to an exemplary embodiment of the present invention. As shown,emitted light radiation 100 from LED 102 hits wavelength-convertingmaterial 104. Some of the emitted light radiation 100 from the LED 102is reflected by the wavelength-converting material 104 as backtransferred unconverted radiation 106. Another portion of the emittedlight radiation 100 from the LED 102 is converted by thewavelength-converting material 104 and emitted rearward as backtransferred converted radiation 118. Some of the emitted light radiation100 from the LED 102 is passed through the wavelength-convertingmaterial 104 as forward transferred unconverted radiation 108, whilesome is passed through as forward transferred converted radiation 114.Furthermore, the wavelength-converting material 104 may emit forwardscattered converted radiation 116 and back scattered converted radiation120. The back scattered converted radiation 120 and back transferredconverted radiation 118 are collectively considered back transferredwavelength-converted radiation 112, while the forward scatteredconverted radiation 116 and the forward transferred converted radiation114 are collectively considered forward transferred wavelength-convertedradiation 110. Use of the SPE technique, which positions the lightsource remote from the wavelength-converting material, enables improvedextraction of the reflected unconverted 106 and transferred unconverted108 photons, reflected converted 118 and transferred converted 114photons, and forward scattered converted 116 and back scatteredconverted 120 radiation converted by the wavelength-converting material104.

An optic element may occupy the space separating the LED and thewavelength-converting material. In some embodiments, an optic elementmay be affixed at one end to the LED light source and at another end tothe wavelength-converting material. The optic element may take anythree-dimensional geometric shape such as, for example, spherical,parabolic, conical, and elliptical. The optic element may also bedescribed as having a cross-sectional shape from the group consisting ofcircular, triangular, hexagonal, trapezoidal, semicircular, andelliptical, among others. The optic element may be a substantiallytransparent and light transmissive medium such as, for example, air,glass, or an acrylic. One or more reflectors may be utilized to receiveand reflect light emitted by the light source and down-converted by thedown-conversion material (i.e., transferred light). The reflector maytake any geometric shape such as, for example, spherical, parabolic,conical, and elliptical, and may be comprised of a variety of reflectivesurfaces known in the art. Additionally, the reflectors may be singleunits or compound units which include multiple reflective surfaces eachhaving their own geometric shape, transmissiveness, and materialcomposition. For example, the reflectors may be aluminum, plastic with avaporized aluminum reflective layer, or any other kind of reflectivesurface. The reflector is positioned to reflect the down-converted lightand may be separate from, or adjacent to, the down-conversion material.More than one reflector may be utilized, separately or as part of acompound reflector having multiple geometric configurations, in someembodiments.

In some embodiments of the present invention, the reflector may be anoptic element, such as a glass, that has been treated to impartreflective characteristics to the optic element. For example, thereflector may be an optic element upon which a thin film has beendeposited or otherwise applied. Such reflectors are known in the art asdichroic filters, thin-film filters, or interference filters, and areoften used to selectively pass light of a small range of colors whilereflecting other colors. By comparison, dichroic mirrors tend to becharacterized by the color(s) of light that they reflect, rather thanthe color(s) they pass. For simplicity, reflectors treated in this wayare referred to collectively herein as “dichroic reflectors” as they mayselectively, and concurrently, allow some light to pass while reflectingother light. Such dichroic reflectors may be selective, for example, forparticular wave-lengths, heat, light, or for other characteristics ofthe radiation emitted by the light source, as is known in the art. Thereflectors and optic elements of the present invention can have varyingdegrees of transmissiveness, i.e., they can be chosen to permit orreflect any range of radiation. For example, the optic elements may beentirely translucent and permit all light radiation to pass through. Asis known to one having ordinary skill in the art, however, even entirelytranslucent optic elements may have some de minimis amount of reflectivecharacteristics (e.g., clear glass has been found to reflect about 4% oflight radiation) which is thought to be intrinsic of the optic element.Alternatively, the optic element may be entirely reflective and notpermit any light radiation to pass through. Additionally, the opticelements and reflectors of the present invention may be prepared suchthat they have some portions with a particular amount oftransmissiveness and other portions that permit or reflect a differentamount of light radiation. Accordingly, each optic element or reflectormay possess the same level of transmissiveness throughout or havedifferent portions with varying levels of transmissiveness. Any range oftransmissiveness of the optic element can be enabled by a number ofmeans known in the art.

In at least one embodiment of the present invention, thewavelength-conversion material is applied to, and contained on, theoptic element or reflector using conventional techniques known in theart. In another embodiment, the wavelength-conversion material, such asa down-converting material, is integrated into the optic element orreflector. For example, an acrylic optic element may be fabricated whichincorporates down-converting materials, such as phosphors, during theacrylic fabrication process, thereby producing an integrateddown-conversion optic element.

As detailed above with regard to FIG. 1, the wavelength-conversionmaterial may transmit, convert, or reflect light radiation. Some lightradiation may be reflected back towards the light source as unconvertedlight radiation. The converted light may be forward transferred or backtransferred. Additionally, some light may be transferred through thewavelength-conversion material without being converted (i.e.,unconverted transmitted radiation). By capturing both the forwardtransferred portion and the back transferred portion of thedown-converted light, system efficiency is improved. Similarly, theposition of the down-conversion material and the reflector, when one ormore reflectors are utilized, may be adjusted to ensure that light fromthe light source impinges the down-conversion material uniformly toproduce a uniform white light and allowing more of the light to exit thedevice. At the same time, positioning the down-conversion materialremote from the light source prevents light feedback back into the lightsource. As a result, the heat at the light source is further minimizedand results in improved light output and life. All of these structuralparameters and features enable increased light production, enhancedlighting efficiency, and improved energy utilization in comparison toknown technologies.

The solid-state light emitting device of the present invention mayfurther include other components that are known in the art. For example,the SSL device may further include an electronic driver. Most SSLsources are low voltage direct current (DC) sources. Therefore anelectronic driver is needed to condition the voltage and the current foruse in the SSL-based light fixture. Alternatively, there are severalalternating current (AC) SSL sources, such as AC-LEDs sold under tradename of “Acriche” by Seoul Semiconductor, Inc. of Seoul, South Korea. Inthese cases the SSL source (e.g., the LED or LED array) can be directlyconnected to the AC power available from the grid. Thus embodiments ofthe present invention may optionally include an electronic driver, atleast a portion of which is inside the base of the light fixture,depending on the type of SSL source employed in the SSL-based lightfixture. The present invention may further include at least oneelectronic conductor such as a connection wire. The electronic conductormay be disposed within the optic element to couple electrical currentbetween the light fixture base and the light source.

The light fixtures of the present invention may be utilized in anyarrangement. For example, at least one embodiment of the presentinvention is a suspended or overhead light fixture. In such anembodiment, the light fixture may have one or more suspension mechanismssuch as suspension rods, cables, or flanges. In another embodiment ofthe present invention, the light fixture is a wall-mounted lightfixture. In such an embodiment, the light fixture may be mountedhorizontally, vertically, or in any other fashion necessary to achievethe desired aesthetic and light output. In a further embodiment, thepresent invention is a system which includes one or more light fixtures.In such an embodiment, the light system may include a number of similarlight fixtures or different light fixtures. One or more embodiments ofthe present invention may be configured to be suspended, wall-mounted,or both. For example, some embodiments of the present invention may beconfigured to work as both an overhead suspended light fixture or as awall-mounted light fixture, with the suspension mechanisms and othercomponents able to accommodate either configuration. Additionally,depending on the amount of illumination desired in the lighted area andon other factors, such as visual aesthetics, the embodiments of thepresent invention may be installed with the optic elements or reflectorspointing towards, or away from, the lighted area. These embodiments maybe better understood in view of the figures, which are described below.

FIG. 2(a) is an illustration of a suspended or overhead solid-statelight source light fixture, in accordance with one embodiment of thepresent invention. The suspended light fixture shown in FIG. 2(a) isconsidered to be an extruded light fixture configuration, because thecross-sectional profile of the light fixture is substantially uniformalong its horizontal axis. The term “extruded” is not intended toconfine this embodiment of the present invention to any specificmanufacturing process, such as an extrusion process, or to the resultthereof. Instead, the extruded SPE light fixture of the presentinvention and its individual components may be manufactured by a numberof known methods. The term “extruded” is used herein to instead refer tothe configuration of the SPE light fixture which has a fixedcross-sectional profile but elongated side. Of course, other embodimentsmay show variations in the cross-sectional profile along the horizontalaxis. As shown, the light source of the light fixture includes aplurality of emitters in an LED array 212. The LED array 212 ispositioned within an angle of a triangular cross-section optic element206 having a concave surface remote from the light source. The LED arrayemits light radiation downwards toward the concave surface of the opticelement, upon which a wavelength-converting material 204 is deposited.The light fixture further includes two parabolic reflectors 208, whichare positioned above the optic element 206 and the LED array 212. Thereflectors reflect light, which has been emitted by the LED array anddown-converted and back transferred towards the reflectors, to thedesired environment, i.e., a lighted area. This embodiment is furtherdetailed in FIG. 2(b), which illustrates a cross-sectional view of thesolid-state light source light fixture shown in FIG. 2(a). As shown, theLED array (which is shown in this view as one LED emitter 202) emitslight radiation downwards towards a wavelength-conversion material 204which includes a down-converting material. The wavelength-conversionmaterial 204 is deposited on a concave surface of the triangularcross-section optic element 206. A wavelength-converting material layermay also be coated on the other walls of the optics, if necessary forthe particular light fixture configuration, light efficiency, andoutput. Some of the emitted light radiation 214 is down-converted andtransferred forward, as forward transferred light 220, through theconcave surface of the optic element 206. Some of the emitted lightradiation 214 is down-converted and transferred rearward, as backtransferred light 222, through the side walls of the optic element 206towards the reflectors 208, where the converted light radiation isreflected. In the illustrated embodiment, reference numbers 214, 220,and 222 identify light beams, not physical elements, and are not claimedcomponents of the invention.

The direction of light rays impinging on the reflector is desirably inthe same direction as light rays that have been transmitted through thedown conversion layer. Consequently, the total light output of thefixture may be a combination of light transmitted through thedown-conversion material and back transferred rays. However, dependingon the reflector size, geometric shape, and distance from the opticalelement, some back transferred rays from the wavelength-convertingmaterial may impinge on the ceiling or walls without hitting thereflector. Such upward rays would be useful for an indirect-direct typelight fixture, which will result in an increased illumination of theupper space of the room.

The wavelength-converting material which is deposited on the concavesurface of the optic element, in this embodiment, may be enclosed by theoptic element to prevent detrimental dust accumulating which coulddecrease the overall light output of the fixture over time. As statedabove, a wavelength-converting material is a material that absorbsradiation in one spectral region and emits radiation in another spectralregion. In an exemplary embodiment, wavelength-converting material maycomprise a single wavelength-converting material. In an alternativeembodiment, the wavelength-converting material may comprise more thanone wavelength-converting materials. Multiple wavelength-convertingmaterials are capable of converting the wavelength emitted from theemitters to the same or different spectral regions. In exemplary oralternative embodiments, the wavelength-converting material may compriseone or more phosphors such as yttrium aluminum garnet doped with cerium(YAG:Ce), strontium sulfide doped with europium (SrS:Eu), YAG:Cephosphor doped with europium; YAG:Ce phosphor plus cadmium selenide(CdSe) or other types of quantum dots created from other materialsincluding lead (Pb) and silicon (Si); among others. In an alternativeembodiment, the phosphor layer may comprise other phosphors, quantumdots, quantum dot crystals, quantum dot nano crystals, or otherdown-conversion materials. The wavelength-converting material may be adown-conversion crystal instead of powdered material mixed with abinding medium. The wavelength-converting material layer may includeadditional scattering particles, such as micro spheres, to improvemixing of light of different wavelengths. In an alternative embodiment,the wavelength-converting material may be comprised of multiplecontinuous or discrete sub-layers, each containing a differentwavelength-converting material. Wavelength-converting materials may beformed by, for example, mounted, coated, deposition, stenciling, screenprinting, and any other suitable technique. Wavelength-convertingmaterial may be formed partially on one wall of the optics. All of theembodiments disclosed in this application may use any of the phosphorsdescribed herein.

Additional benefits can be achieved through the use of a heat sink. Theembodiment shown in FIGS. 2(a)-2(c) is a suspended or overhead lightfixture, which is affixed to a surface by one or more suspensionmechanisms. For example, suspension wires or rods (hollow or solid) maybe used to hang the light fixture. The suspension mechanisms may alsoinclude power cords, control wires, or other aspects which arenecessarily included in light fixtures. Power and control wires for thelight fixture may be connected along with the suspension wires or insidethe rods.

FIG. 2(c) illustrates an expanded view of FIG. 2(b) showing the heatsink 210 and the LED emitter 202. A heat sink 210 is shown to be affixedto the bottom of the LED emitter 202 which, since this embodiment isshown as a suspended or overhead light fixture, actually means that theheat sink 210 is around and above the LED emitter 202. At least aportion of the heat sink 210 is external to the enclosure created by theoptic element 206. The heat sink may comprise a series of fins. The heatsink could alternatively, or additionally, include a mesh that extendsfrom heat sink 210 and surrounds at least a portion of the outer surfaceof the optic element 206 between the LED emitter 202 and the concavesurface of the optic element. The heat sink 210 may be manufactured ofvarious heat dissipation materials known in the art, such as aluminum,copper, and carbon fiber. The heat sink may be painted in a color, forexample painted in white, to enhance or alter the heat dissipationcapability of the material. At least a portion of the heat sink 210 isexternal to the optic element 206, but the heat sink 210 is coupled tothe internal LED emitter 202. This can be achieved, for example, at abreak-through in the optic element at an end substantially opposite theconcave surface of the optic element. This coupling effectively retainsthe LED emitter 202 substantially within the optic element 206 whilealso sealing the optic element 206 closed. Once assembled, the inside ofthe optic element 206 may be a solid, a vacuum, or may be filled withair or an inert gas.

FIG. 3 is an illustration of a solid-state light source light fixture,in accordance with another embodiment of the present invention. Such alight fixture may be considered a pendant light fixture, as it issuspended by only one suspension mechanism. The pendant light fixtureshown in FIG. 3 is also considered to be a revolved light fixtureconfiguration, since the cross-sectional profile of the light fixture issubstantially uniform as it is circumferentially rotated around itsvertical axis. Of course, other embodiments may show variations in thecross-sectional profile as the light fixture is rotated around itsvertical axis. In the embodiment shown in FIG. 3, an LED array 312 ispositioned to emit light radiation downwards towards a remotewavelength-conversion material 304 which is deposited on aconical-shaped transmissive optic element 306. A conical-shapedreflector 308 is inversely affixed atop the LED array 312 and opticelement 306 so as to provide an hour-glass appearance to the completelight fixture 300. A heat sink 310 is adjacent or affixed to the LEDarray 312 between the reflector 308 and the optic element 306. In thisembodiment, the pendant-style light fixture 300 is suspended in thelighting location by a singular suspension mechanism 330. The heat sink310 may be used to mechanically support the radiation emitting lightsource, an LED array 312 in this embodiment, and utilized for heatdissipation purposes.

FIGS. 4(a)-4(f) illustrate cross-sectional views of various lightfixture configurations featuring one or more light sources, wave-lengthconversion materials, heat sinks, optic elements, and reflectors, inaccordance with other embodiments of the present invention. As shown,the light source may be one light emitter positioned between thereflectors and the optic elements. FIG. 4(a) shows an embodiment inwhich one light emitter is used to direct light towards awavelength-conversion material deposited on, or integrated with, atriangular-shaped optic element. FIGS. 4(a) and 4(f) show embodiments ofthe present invention in which the wavelength-conversion material may bedeposited on, or integrated with, one or more surfaces of the opticelement. As discussed above and shown in FIGS. 4(a)-4(f), the opticelement may take a number of other shapes. In each of the light fixtureembodiments shown in FIGS. 4(a)-4(f), some light radiation emitted bythe light source may be reflected back towards the light source asunconverted light radiation. The converted light may be forwardtransferred or back transferred. Additionally, some light may betransferred through the wavelength-conversion material without beingconverted (i.e., unconverted transmitted radiation). By capturing boththe forward transferred portion and the back transferred portion of thedown-converted light, system efficiency may be improved. Similarly, theposition of the down-conversion material and the reflector, when one ormore reflectors are utilized, may be adjusted to ensure that light fromthe light source impinges the down-conversion material uniformly toproduce a uniform white light and allowing more of the light to exit thedevice. At the same time, positioning the down-conversion materialremote from the light source prevents light feedback back into the lightsource. As a result, the heat at the light source is further minimizedand results in improved light output and life. The shape of the opticelement and the reflectors, as well as the position and number of lightemitters, can be configured in any way to achieve increased lightproduction, enhanced lighting efficiency, and improved energyutilization in comparison to known technologies.

FIGS. 5(a)-5(c) illustrate cross-sectional views of various lightfixture configurations featuring one or more light sources, wave-lengthconversion materials, heat sinks, optic elements, and reflectors, inaccordance with other embodiments of the present invention. As shown, anumber of light sources may be used. For example, FIGS. 5(a)-5(d) showembodiments having multiple light emitters 502 each. FIG. 5(a) shows anembodiment in which two light emitters 502 are used to direct lighttowards a wavelength-conversion material deposited on, or integratedwith, a pentagonal-shaped optic element. The light emitters 502 areaffixed to heat sinks 510. The light emitters 502 are positioned on oneor more surfaces of the optic element 506 that are substantiallyopposite of the surface of the optic element on which thewavelength-conversion material 504 is deposited. In this configuration,the light emitters 502 are positioned between the wavelength-conversionmaterial 504 and the reflectors 508. The light emitters 502 emit lightradiation towards the wavelength-conversion material 504, where at leastsome light radiation is converted and back-transferred in the directionof the light emitters. The reflectors 508 are positioned to reflect atleast a portion of the back-transferred converted light radiation to thedesired environment, i.e., a lighted area. In the configuration shown inFIG. 5(a), it is the back-transferred converted light radiation that isreflected by the reflectors and used, in addition to the forwardtransferred converted light radiation, to illuminate the desired area.

The pentagonal-shaped optic element shown in FIG. 5(a) is inverted inFIG. 5(b). FIGS. 5(c) and 5(d) show further configurations of the lightfixture in accordance with at least one embodiment of the presentinvention. The optic elements shown in FIGS. 5(c) and 5(d) may also beconsidered pentagonal-shaped optic elements, but with an internallydepressed triangular profile instead of an externally pointed triangularprofile. In each of the light fixture embodiments shown in FIGS.5(a)-5(d), multiple light emitters 502 are used, which are each affixedwith a heat sink 510. FIG. 5(b) shows an embodiment in which thewavelength-conversion material 504 is deposited on, or integrated with,one surface of the optic element 506, while FIG. 5(c) shows anembodiment in which the wavelength-conversion material 504 is depositedon, or integrated with, multiple surfaces of the optic element 506. Inthe embodiment shown in FIG. 5(d), the wavelength-conversion material504 is deposited on a single surface of the optic element 506 that isperpendicular to the surfaces having the light emitters 502. In theembodiments shown in FIGS. 5(a)-5(d), some light radiation emitted bythe light emitters 502 may be reflected back towards the light source asunconverted light radiation. The converted light may be forwardtransferred or back transferred. Additionally, some light may betransferred through the wavelength-conversion material without beingconverted (i.e., unconverted transmitted radiation). In the embodimentsshown in FIGS. 5(b) and 5(c), the wavelength-conversion material isdeposited on one or more surfaces of the optic element which are betweenthe light source and the reflectors. In such embodiments, the reflectorscapture and reflect the forward transferred portion of thedown-converted light radiation. The back-transferred portion of thedown-converted light radiation is allowed to pass through thetransmissive surfaces of the optic element. By capturing both theforward transferred portion and the back transferred portion of thedown-converted light, system efficiency may be improved. As above, theshape of the optic element and the reflectors, as well as the positionand number of light emitters, can be configured in any way to achieveincreased light production, enhanced lighting efficiency, and improvedenergy utilization in comparison to known technologies.

The light fixtures of the present invention may incorporate one or morereflectors having a myriad of shapes and sizes. FIGS. 6(a)-6(c)illustrate cross-sectional views of various light fixtures havingreflectors of different shapes, in accordance with other embodiments ofthe present invention. Such reflectors may be used with bothextruded-style light fixtures, as shown for example in FIG. 2(a) and inFIGS. 6(a)-6(c), and with revolved-style light fixtures, as shown inFIG. 3. In addition to extruded or revolved fixtures, the optic elementof the SPE light fixtures of the present invention may have a number ofsides. For example, the optic element may have a square, rectangular,trapezoidal, pentagonal, hexagonal, or octagonal shape, among otherstructural shapes. Optic elements having any of these structural shapesmay be incorporated into any of the embodiments of the presentinvention.

FIGS. 7(a) and 7(b) illustrate another exemplary embodiment of theinvention using the SPE technique which feature an array of emitters712. FIGS. 7(a) and 7(b) illustrate the embodiments when used as a wallsconce and as a suspended pendant fixture, respectively. Here, the wallor ceiling to which the light fixture is mounted may behave as areflector. FIG. 7(c) shows the cross-sectional view for bothembodiments. As shown, the SPE light fixture includes optic element 706deposited with a layer of wavelength-converting material 704. Areflector 708 having a high amount of transmissiveness (i.e., a lowreflective coating), such as a translucent cover, may be used to controlthe output spectrum of the light fixture as well as provide desiredaesthetics. FIG. 7(d) illustrates an expanded view of FIG. 7(c) showingthe heat sink, optic elements, and the solid-state light emitting diode(LED). An LED or an LED array may be mounted on a heat sink. Amechanical part or suspension mechanism may be used to support the heatsink and affix the light fixture to the wall or ceiling.

FIG. 8(a) illustrates yet another exemplary embodiment of the inventionusing the SPE technique. It illustrates another high efficiency lightingfixture that uses solid-state light emitter(s) and a remotewavelength-converting material. FIG. 8(b) is the sectional-view of thefixture in FIG. 8(a). As shown, the fixture includes awavelength-converting material 804 that is remote from light radiationemitter(s) 802. Both the emitter(s) 802 and the wavelength-convertingmaterial 804 are affixed to, or integrated with, optic elements 806. Thewavelength-converting material 804 may be a phosphor. A reflector 808may be used to control the output beam distribution and to improve thecolor uniformity the beam. Heat sink 810 may be used for mounting theemitter(s) 802 and for heat dissipation, as discussed above. Asuspension mechanism 830 is used to suspend the wavelength-convertingmaterial 804 above the emitter(s) 802 within the enclosure created bythe optic elements 806. The suspension mechanism 830 may also be used tomount the SPE light fixture to the wall or ceiling. For a number ofreasons, including improved beam control, light efficiency, andaesthetics, multiple reflectors may be used separately or together ascompound reflective surfaces. FIG. 8(c) illustrates a cross-sectionalview of an embodiment incorporating a compound reflector 808. Typicalapplications for the SPE light fixtures shown in FIGS. 8(a)-8(c) arerecessed, pendant, and track down-light fixtures.

FIGS. 9(a) and 9(b) illustrate a further embodiment of the presentinvention which includes a number of SPE light fixtures as a SPE lightsystem or assembly. A SPE light system may be composed of a one or moreSPE light fixtures, such as those shown in FIGS. 2-8. The SPE lightfixture within this SPE light system may be same or different. Theindividual SPE light fixtures may be connected via optic elements,reflectors, heat sinks, suspension mechanisms, or via other knowncomponents, as would be appreciated by one having ordinary skill in theart.

The amount of heat from the LED light source and other necessaryelectronic elements going into the light fixture limits the totalcapacity of the LEDs that can be used with reliable performance and,therefore, limits the amount of light that is produced. Embodiments ofthe present invention place the LED source and heat sink in a manner todissipate more of the heat produced by the LEDs into the environment.This arrangement enables a greater amount of light to be produced whileensuring that the proper operating temperatures for the LEDs andelectronic elements are maintained. This arrangement may be even morebeneficial for applications where the SPE light fixture is used in openluminaires, when compared to benefits achieved in completely enclosedluminaires.

As stated before, the radiant energy hitting the down conversionmaterial will be converted to a higher wavelength radiation and whenmixed it will provide white light similar to the light produced bytraditional light fixtures. The spectrum of the final light outputdepends on the wavelength-conversion material. The total lightextraction depends on the amount of light reaching thewavelength-conversion layer, the thickness of the wavelength-conversionlayer, and the materials and design of the optic elements andreflectors. These components can be shaped and sized in any mannedcontemplated to achieve the performance and aesthetic goals of the SPElight fixture. The Example and Table below detail efficiency and lightradiation improvements enabled by the SPE light fixtures of the presentinvention.

EXAMPLE

In at least one embodiment of the present invention, an LED package withSPE technique is implemented. Unlike a typical conventional white LEDpackage, where the down conversion phosphor is spread around the lightsource or die, in the SPE package of the invention the phosphor layer ismoved away from the die, leaving a transparent medium between the dieand the phosphor. An efficient geometrical shape for such packages maybe determined via ray tracing analysis. It is worth noting that the SPEpackage requires a different phosphor density to create white light withchromaticity coordinates similar to the conventional white LED package.This difference is a result of the SPE package mixing transmitted andback-reflected light with dissimilar spectra, whereas the conventionalpackage uses predominantly the transmitted light.

Computer simulations were conducted to determine the light outputimprovement using a SPE light fixture according to the embodiments ofthe present invention. A light fixture model shown in FIG. 10(a) wassetup in a ray-tracing software. The light fixture model shown in FIG.10(a) is similar to that shown in FIG. 2(a), without one or morereflectors. For clarity, the configuration of the analyzed light fixturewill be detailed with reference to FIG. 2(a). The blue LED array 212 wasenclosed by a clear optic element 206. A phosphor wavelength-convertingmaterial 204 was attached or deposited onto the concave surface at thebottom of the optic element 206. The phosphor density was selected toachieve 6500 kelvin correlated color temperature (CCT) on the black-bodylocus of the 1931 CIE diagram.

FIG. 16 illustrates a few traced rays of the model. Another lightfixture was modeled by changing the blue LEDs to same number of whiteLEDs. The phosphor layer was changed to a diffuser with the samedimensions. The white LEDs consist of the blue LED dies and phosphorspread around the blue LED dies. The radiant energies and emitting beamangles are the same from the blue LED dies in the white LEDs and fromthe blue LEDs used in the SPE light fixture. The CCT values and thechromaticity coordinates are the same in the white LEDs and in the SPElight fixture. Table 1 below shows the results of this comparativeanalysis:

TABLE 1 Results of comparative analysis. Luminous flux CCT CIE (x, y)(lm) SPE fixture 6300K (0.316, 0.333) 541.3 White-LED fixture 6293K(0.315, 0.334) 416.2

As shown in Table 1 above, the simulations demonstrated that the SPElight fixture has about 30% more light than the fixture using white LEDswhen the CCT and the chromaticity coordinates are the same in bothconfigurations.

Accordingly the present invention relates to a highly efficientSPE-based lighting fixture that includes solid-state radiation emitters(e.g., LEDs), a wavelength-converting material (e.g., a phosphor), and areflector. The wavelength-converting material is placed away from theLEDs. The back transferred photons from the wavelength-convertingmaterial can be extracted to increase the overall efficiency of thefixture. Therefore, the fixture requires fewer LEDs or less electricalenergy, and can cost less to manufacture.

It will be understood that the geometry of the SPE light fixtures of thepresent invention is not limited to the specific shapes shown in theFigures, described above, or presented in the Examples. Alternate shapesmay be used to achieve specific performance or aesthetics, whileaddressing other design concerns, such as light color and light sourcelife. Although the invention has been described with reference toexemplary embodiments, it is not limited thereto. Rather, the appendedclaims should be construed to include other variants and embodiments ofthe invention which may be made by those skilled in the art withoutdeparting from the true spirit and scope of the present invention.

What is claimed:
 1. A light fixture comprising: a heat sink; an opticelement made of a light transmissive material and having a first surfaceand a second surface which is not coplanar to the first surface, whereinthe first surface and the second surface are inclined against the heatsink; a light source connected to the heat sink and not directlyconnected to the optic element; a reflector arranged above the lightsource, the heat sink, and the optic element; and awavelength-conversion material arranged between the light source and thereflector.
 2. The light fixture of claim 1, wherein the heat sink has aportion exposed to air.
 3. The light fixture of claim 1, wherein thelight fixture is a wall-mounted fixture or a suspended fixture.
 4. Thelight fixture of claim 1, wherein the light source is remote from thewavelength-conversion material.
 5. The light fixture of claim 1, whereinthe optic element has a cross-sectional shape selected from the groupconsisting of circular, triangular, hexagonal, trapezoidal,semicircular, and elliptical.
 6. The light fixture of claim 1, whereinthe light source is able to be driven by direct current or alternatingcurrent.
 7. The light fixture of claim 1, wherein the reflectorcomprises a parabolic reflective surface.
 8. The light fixture of claim1, wherein the optic element comprises a break between the first surfaceand the second surface for structurally connecting to the heat sink. 9.The light fixture of claim 1, wherein the first surface and the secondsurface are oriented to face the reflector.
 10. The light fixture ofclaim 1, wherein the optic element has a third surface on which thewavelength-conversion material is disposed.
 11. The light fixture ofclaim 10, wherein the third surface is inclined against the firstsurface.
 12. The light fixture of claim 1, wherein the heat sinkcomprises a mesh extending from the heat sink to affix the opticelement.
 13. The light fixture of claim 1, wherein the heat sinkcomprises a series of fins.